• 설비공학논문집
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• 제18권3호
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• pp.279-286
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• 2006

The present study concerns the annual performance evaluation of a hybrid-renewable energy system with geothermal and solar heat sources for hot water, heating and cooling of the residential buildings. The hybrid energy system consists of ground source heat pump of 2 RT for cooling, solar collectors of $4.8m^2$, storage tank of 250 liters and gas fired backup boiler of 11.6 kW. The averaged coefficients of performance of geothermal heat pump system during cooling and heating seasons are measured as 4.1 and 3.5, respectively. Also solar fraction for hot water is measured as 35 percent. Overall, the results shows that the hybrid-renewable energy system satisfactorily operated under all climatic conditions.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1353-1357
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• 2008

A sea water source cascade heat pump was designed and tested in this study. The system was designed to perform a single stage operation in summer, as well as a cascade operation in winter to ensure the high temperature lift. A steady-state simulation model was developed to analyze and optimize its performance. The simulation results show that the R717 exhibits best performance among combinations considered in this study. A R410A also exhibits the highest performance among HFCs with the smallest compressor displacement. A 15-RT R410A-R134a pilot system was installed in the 5-story commercial building at Samcheok City by the East Sea. A scroll type R410A compressor, a reciprocating type R134a compressor, plate type condenser/ evaporator/ cascade heat exchanger and two electronic expansion valves were used to build a pilot. A titanium plate type heat exchanger is also used for the heat exchanging with a sea water. The heat source/sink water is supplied from the well below the seashore in the depth of 5 m. In the initial test of the system, supply water temperature was rising up to $67^{\circ}C$ using a sea water heat source of $9^{\circ}C$, while an ambient temperature was $4.5^{\circ}C$.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1447-1454
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• 2009

Currently, geothermal heat pump systems are being installed in new official and commercial building, welfare facilities, and school but there are a few cases for the housing heat sink in Korea. The reason is that there are no progressive taxes for the household electrical use, no actual output for the application of geothermal technology, high initial investment. For the overall use in multi family apartment such as the Green Home etc, technology development and building of the relevant research team need to be done through preliminary study. Core subjects for overall use include cooling heating load estimation for the multi family apartment, economical efficiency of the geothermal cooling and heating system, design and construction technology of the geothermal cooling and heating system for the multi family apartment, commercialization plan, and state of the art analysis. Selection of the detailed subjects with respect to core subject, driving schedule and commercialization plan, driving system, presentation of the utilization plan.

• 한국태양에너지학회 논문집
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• 제34권3호
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• pp.75-81
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• 2014

Recently, the use of renewable energy has been attracted due to the interest in energy-saving and the reduction of CO2 emission. In order to reduce the energy consumption of the cooling and the heating in the field of the architectural engineering, heat pump systems using renewable energy have been developed and used in various applications. In many researches, integrated heat pump systems are suggested which use solar and geothermal heat as the heat source for cooling and heating. However, it is still difficult to predict the performance of the systems, because the characteristic of heat exchange in each system is complicated and various. In this system, the performance prediction simulation of the heat pump was developed using a dynamic simulation model. This paper describes the summary of the suggested systems and the result of the simulation. The average temperature of the heat source, heating loads and COP were calculated with the cases of different local conditions, different system composition and different operation time by TRNSYS 17.

• Advances in Energy Research
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• 제4권1호
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• pp.87-106
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• 2016

In this research, optimum design of the combined solar collector, geothermal heat pump and thermal seasonal storage system for heating and cooling a sample greenhouse is studied. In order to optimize the system from technical point of view some new control strategies and functions resulting from important TRNSYS output diagrams are presented. Temperatures of ground, rock bed storage, outlet ground heat exchanger fluid and entering fluid to the evaporator specify our strategies. Optimal heat storage is done with maximum efficiency and minimum loss. Mean seasonal heating and cooling COPs of 4.92 and 7.14 are achieved in series mode as there is no need to start the heat pump sometimes. Furthermore, optimal parallel operation of the storage and the heat pump is studied by applying the same control strategies. Although the aforementioned system has higher mean seasonal heating and cooling COPs (4.96 and 7.18 respectively) and lower initial cost, it requires higher amounts of auxiliary energy either. Soil temperature around ground heat exchanger will also increase up to $1.5^{\circ}C$ after 2 years of operation as a result of seasonal storage. At the end, the optimum combined system is chosen by trade-off between technical and economic issues.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.169.1-169.1
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• 2010

Geothermal heat pump(GHP)system has been extensively disseminated due to the recent increasing demand over new and renewable energy. However, the economics and system reliability has been key issues and barriers to insure a better system performance as designed originally. The building integrated designs of geothermal heat pump system are test and optimize GHP system by evaluating its performance in virtual reality. System design is an iterative process that will help optimize the cost efficiency of the system. One of the primary goals is to minimize the energy imbalance between the amount of energy extracted from the ground and the energy reject to it. This will reduce the land area required to install the GHX, reduce the cost of installing it and ensure the long-term efficiency of the system. Commissioning is the process of ensuring that are designed, installed, functionally tested, and capable of being operated and maintained to performance in conformity with design intent. In this paper, Study on introduction of Initial commissioning method of Geothermal Heat Pump(GHP) system using ISO performance data has been introduced. Also KIER GHP Simulator is used to simulate actual heat pimp operating condition and test commissioning method. Result should that the experiment data base could verify the applicability of the commissioning method, and also were able to suggest a better ways to GHP commissioning.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1395-1400
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• 2004

A centrifugal compressor for geothermal heat pump system using R134a as working fluid has been developed. The centrifugal compressor consists of an impeller with splitters, two vaneless diffuser, a low solidity vaned diffuser and a volute. In this compressor, diffuser blade angles are controlled to satisfy both heating and cooling conditions. A aerodynamic design was done by applying the repeating design procedure including a meanline design, a 3D geometry generation and fluid dynamic calculation. In this paper, design and performance prediction results of the compressor are presented.

• 한국태양에너지학회 논문집
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• 제28권3호
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• pp.7-14
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• 2008

400RT geothermal system which is the biggest capacity among on-operations at present in Korea is measured and evaluated on 23rd${\sim}$26th Jan. 2008 during those days building is not allowed owners and/or tenants to move in. The geothermal system is consist with vertical-typed 112 geothermal heat exchangers which are installed circle-like 1 row with 4m interval, and has 16 units of 25USRT geothermal-source heat pump(GSHP)s. And each 5 units of circulation pump are running for geothermal heat exchangers and hot water supplies. The followings are the results. The temperatures at G.L. -70m of 2 boreholes are varied quite similarly. The average temperature difference between inlet and outlet of geothermal pipes is $4.1^{\circ}C$, and that of hot water supply is $3.2^{\circ}C$, of Zone 3's each 4 GSHPs when being operated. Despite temperature fluctuations by heating loads, the average temperature difference between main pipes of inlet and outlet of geothermal heat exchangers is measured as $4.1^{\circ}C$. This study propose "Geothermal System COP" which includes not only consumed electric power by compressor but also circulation pumps and auxiliary utilities. By comparing the geothermal system COP with GSHP's performance specification, it is clear that the performances of GHSPs of this site are satisfied with the specification.

• 한국지열·수열에너지학회논문집
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• 제12권1호
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• pp.7-16
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• 2016

This paper presents the measurement and analysis results for the cooling performance of ground-coupled heat pump (GCHP) system using a cooling tower as a supplemental heat rejector. In order to demonstrate the performance of the hybrid approach, we installed the monitoring equipments including sensors for measuring temperature and power consumption, and measured operation parameters from May 1 to October 30, 2014. The results showed that the entering source temperature of brine returning from the ground heat exchanger was in a range of design target temperature. Leaving load temperatures to building showed an average value of $11.4^{\circ}C$ for cooling season. From the analysis, the daily performance factor (PF) of geothermal heat pumps ranged from 4.4 to 5.2, while the daily PF of hybrid GCHP system varied from 3.0 to 4.0 over the entire cooling season.

• 한국지열·수열에너지학회논문집
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• 제17권4호
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• pp.68-78
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• 2021

In order to solve the increasing deterioration of the energy shortage problem, ground-source heat pump (GSHP) systems have been widely installed. The control method is a significant component for maintaining the long-term performance and for reducing operation cost of GSHP systems. This paper presents the measurement and analysis results of the cooling performance of a GSHP system using capacity control with outdoor air temperature. For this, we installed monitoring equipments including sensors for measuring temperature, flow rate and power consumption, and then monitored operation parameters from July 9, 2021 to October 2, 2021. From measurement results, we analyze the effect of capacity control with outdoor air temperature on the cooling performance of the system. The average performace factor (PF) of the heat pump was 6.95, while the whole system was 5.54 over the measurement period. Because there was no performance data of the existing GSHP system, it was not possible to directly compare the existing control method and the outdoor air temperature method. However, it is expected that the performance of the entire system will be improved by adjusting the temperature of cold water produced by the heat pump, that is, the temperature of cold water on the load side according to the outside air temperature.